Invasive examinations refer to various biopsies and puncture examinations, including: tracheoscopy, ultrasound endoscopic puncture biopsy, CT or ultrasound-guided puncture biopsy, thoracocentesis pleural fluid cytology, puncture biopsy or surgical biopsy of metastatic nodes, mediastinoscopic mediastinal lymph node biopsy, etc. Non-invasive examinations mainly refer to various imaging examinations, nuclear medicine examinations, blood tests and sputum tests to find cancer cells, including: chest or thoracoabdominal CT examinations, ultrasound examinations, brain MRI examinations, bone isotope scans and the more expensive whole-body PET/CT, as well as blood tumor markers, liver and kidney functions and routine blood tests. The purpose of invasive and non-invasive examinations are not exactly the same. Non-invasive tests mainly indicate the location and shape of the tumor and know whether there is metastasis elsewhere, while blood tests can provide an objective understanding of the body’s functional status. The advantage is that it is easy to perform, almost non-invasive and does not require anesthesia; the disadvantage is that non-invasive tests cannot directly detect tumor cells except for a small number of patients who can find cancer cells in sputum. Non-invasive tests cannot confirm the diagnosis of lung cancer, including the expensive whole-body PET/CT tests, which only have an accuracy rate of about 80%, meaning that more than 20% of patients diagnosed with lung cancer through non-invasive tests are not tumors at all. This is the problem to be solved by various invasive tests, which aim to try to obtain biopsies and find cancer cells. The disadvantages of invasive tests are that they are painful for the patient, require some risk, and usually require local or general anesthesia. However, there is no need to worry, as the invasive tests mentioned above have been used for many years and are very safe, and there are almost no major accidents as long as they are performed according to specifications.